In a display device such as a liquid crystal display device, a backlight is provided on a back surface of a display panel. An example of the backlight may be a surface-emitting illumination device using, for example, a light guide plate. In such an illumination device, a reflection plate is provided on back surface side of the light guide plate, and there is proposed a configuration in which the reflection plate is bonded to a back surface of the light guide plate (refer to Patent Literature 1, for example).